prisma

Prisma Patterns

Connection Management: See frameworks/database/connection-management.mdc for general principles.

Connection Management

Core Rules

• NEVER use new PrismaClient() directly in services, handlers, or test files
• ALWAYS use the singleton pattern for production code
• ALWAYS use shared test clients for test code
• NEVER call prisma.$disconnect() on shared clients

Singleton Pattern (Production)

This is THE ONLY place new PrismaClient() should be instantiated in production code:

// lib/prisma.ts - Single source of truth
import { PrismaClient } from '@prisma/client';

const globalForPrisma = globalThis as unknown as {
  prisma: PrismaClient | undefined;
};

export const prisma = globalForPrisma.prisma ?? new PrismaClient({
  log: process.env.NODE_ENV === 'development' ? ['query', 'error', 'warn'] : ['error'],
});

if (process.env.NODE_ENV !== 'production') {
  globalForPrisma.prisma = prisma;
}

export default prisma;

Service Usage

// BAD - creates new client per service instantiation
class UserService {
  private prisma = new PrismaClient();
}

// GOOD - imports singleton
import { prisma } from '@/lib/prisma';

class UserService {
  async getUser(id: string) {
    return prisma.user.findUnique({ where: { id } });
  }
}

// ALSO GOOD - dependency injection for testability
class UserService {
  constructor(private prisma: PrismaClient) {}
}

Connection Pool Configuration

// In schema.prisma or connection string
datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
  // Connection pool settings via URL params:
  // ?connection_limit=10&pool_timeout=30
}

Serverless Configuration (Vercel, AWS Lambda, etc.)

# Use Prisma Accelerate or PgBouncer for serverless
DATABASE_URL="prisma://accelerate.prisma-data.net/?api_key=..."
DIRECT_URL="postgresql://..."  # For migrations only

datasource db {
  provider  = "postgresql"
  url       = env("DATABASE_URL")
  directUrl = env("DIRECT_URL")
}